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Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here


v.db.univar - Calculates univariate statistics on selected table column for a GRASS vector map.


vector, statistics, attribute table


v.db.univar --help
v.db.univar [-eg] map=name [layer=string] column=name [where=sql_query] [percentile=float[,float,...]] [--help] [--verbose] [--quiet] [--ui]


Extended statistics (quartiles and 90th percentile)
Print stats in shell script style
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


map=name [required]
Name of vector map
Or data source for direct OGR access
Layer number or name
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1
column=name [required]
Name of attribute column on which to calculate statistics (must be numeric)
WHERE conditions of SQL statement without 'where' keyword
Example: income < 1000 and inhab >= 10000
Percentile to calculate (requires extended statistics flag)
Options: 0-100
Default: 90

Table of contents


v.db.univar calculates basic univariate statistics for numeric attributes in a vector attribute table. It will calculate minimum, maximum, range, mean, standard deviation, variance, coefficient of variation, quartiles, median, and 90th percentile. It uses to create list values for statistical calculations. NOTES A database connection must be defined for the selected vector layer.


Univariate statistics on attribute table column

In this example, the 30 years precipitation data table is statistically analysed (North Carolina sample dataset) and univariate statistics performed:
# show columns of attribute table connected to precipitation map -c precip_30ynormals

# univariate statistics on 30 years annual precipitation in NC
v.db.univar precip_30ynormals column=annual
 Number of values: 136
 Minimum: 947.42
 Maximum: 2329.18
 Range: 1381.76
 Mean: 1289.31147058823

Univariate statistics on randomly sampled data points

In this example, random points are sampled from the elevation map (North Carolina sample dataset) and univariate statistics performed:
g.region raster=elevation -p
v.random output=samples n=100
v.db.addtable samples column="heights double precision"
v.what.rast samples raster=elevation colum=heights samples

v.db.univar samples colum=heights


db.univar, r.univar, v.univar,, d.vect.thematic


Michael Barton, Arizona State University

and authors of (Markus Neteler et al.)

Last changed: $Date: 2016-05-17 07:10:47 -0700 (Tue, 17 May 2016) $


Available at: v.db.univar source code (history)

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here

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© 2003-2018 GRASS Development Team, GRASS GIS 7.0.7svn Reference Manual